Instrumental Sludge/Doom/Post-Rock band with strong influences from many different underground genres. The combination of brooding melodic soundscapes, ultra-heavy distortion and drone/ambient elements has led to the band sometimes being described as 'Post-Doom'. Their music primarily focusses on creating an intense, dark atmosphere.

The band often abbreviate their name to "HMBSM".
The 2015 versions of 'Portals' only include the Hemelbestormer parts of the original 2014 split release with Vanessa Van Basten, along with a bonus new track.